This invention relates to brush seals. Specifically, the present invention relates to brush seals with adjustable clearances. As used herein, the phrase brush seal clearance refers to the distance that the bristles extend past the plates.
Proper operation of a turbine engine should occur when the myriad engine parts remain within acceptable limits of alignment with other engine parts. The performance of the engine tends to decline when the alignment exceeds these acceptable limits. This is particularly true when dealing with seals.
Many factors influence whether parts maintain proper alignment. Assembly techniques and rotor balancing clearly affect part alignment Unexpected situations, like foreign object damage, can also create misalignments. Misalignment can even occur with normal operation of the engine. Typically, thermal conditions cause this type of misalignment. For example, steam turbine rotors can bow over time.
Conventional methods exist to handle such misalignment. For example, the technician could re-machine certain features of the engine to return to proper alignment. Re-machining features on an installed turbine engine, however, can prove time consuming and costly.
Another method is for the operator to maintain an inventory of spare engine hardware. This allows a technician to replace the misaligned parts rapidly. Likewise, this method can prove expensive in terms of inventory costs.